The ruler of a great North Sea Empire, Cnut united the crowns of England, his native Denmark, and Norway. This was both the apogee of Viking political influence and the tail end of the era. 

Had Cnut not died when he did, in 1035, while in his mid-forties, England and Scandinavia may well have become a long-lasting union. 

As it turned out, his sons Harold Harefoot and Harthacnut only reigned for a couple of years, dying in their early twenties. They were the last Danes to rule England.

Son of Sweyn

The second was born the son of the first, Cnut the offspring of Sweyn Forkbeard, also king of Denmark, England, and Norway, if only for a few weeks from December 1013 until his death in February 1014. 

Born in 963, Sweyn had seized the Danish throne from his father, Harald Bluetooth, when he was barely 20 years old. Harald duly fled into exile and died soon afterward.

Sweyn married a Polish princess, probably named Gunhild, whose details are otherwise sketchy apart from the fact that she was Cnut's mother. A later marriage, to the widow of Eric the Victorious of Sweden, to Sigrid the Haughty, is also found in the Norse sagas.

Sweyn formed an alliance with Erik's son, Olof Skötkonung, against the Norwegian king, Olaf Tryggvason, whom they defeated at the large naval Battle of Svolder in 999 or 1000. This resulting triumph allowed the victors to share Norway between them, Sweyn receiving the Viken district in the south nearest Denmark.

Sweyn brought bishops and priests over from England to minister in Denmark, some of Danish origin. He also built churches, such as the one in Roskilde. Some historians suggest that, while not a particularly religious man, Sweyn suffered a sense of guilt over the treatment of his father.

He led several raids against England in the early 1000s, acquiring plentiful Danegeld without gaining a proper foothold on the island. We know that Cnut was with him on the most successful, extensive, and ultimately last of these raids, in 1013. 

Weeks after Sweyn had claimed the English crown, shortly before Christmas, he died at Gainsborough in Lincolnshire. His body was taken to Denmark for burial, possibly at Roskilde Church or another he had built, at Lund in modern-day Sweden.

The young Cnut

The most commonly agreed date of Cnut's birth is 990, though the place isn't known. One saga describes him as being tall and with a keen sight. 

It is assumed that he would have joined his father on earlier raids of England, too, and his responsibilities in 1013 included overseeing Sweyn's fleet and his army stationed at Gainsborough.

Upon Sweyn's death, while his brother Harald Svendsen inherited the Danish throne for the short time he remained alive, Cnut was accepted as king of England by the Five Boroughs of the Danelaw in the East Midlands. 

This found little favor with the nobility in the south and west, who persuaded Aethelred to return from Normandy and claim the throne.

This he duly did, but only with the help of the Norwegian Olaf Haraldsson, who sailed down the Thames to take London. Leaving Lincolnshire to be avenged by Aethelred's men, Cnut retreated to Denmark.

With him, it is thought in a different ship, the same one as was carrying Sweyn's body, was his wife Aelfgifu of Northampton, and born around the same time as Cnut and from a noble Mercian family. 

Her father, Aelfhelm, had been killed in 1006, probably at the hands of Aethelred, and her brothers blinded. Her family was further persecuted when Sweyn returned in 1013.

With Aelfgifu was her baby son, Cnut's first-born, Svein, later to be crowned king of Norway. 

Return to England

Forming an alliance with Sweden through his father's second wife, the widow of Eric the Victorious, Cnut gathered a large force to cross the North Sea the following year, 1015. Waiting for him was Aethelred's son, Edmund Ironside.

As England had descended into revenge killings and internecine strife following Cnut's previous retreat, Edmund had taken advantage of the chaos and his familial status to assume control of military matters. His older brothers had died, and his father, by now in his late forties, would only live until 1016.

Assuming the throne on St George's Day, the new king fought back wave after wave of Danish attacks, five major battles in all, culminating in victory for the Danes at Assandun in October 1016.

Cnut had already assumed control of Wessex the year before, then much of Mercia, until encircling London once Edmund became king. Edmund had withdrawn to Wessex but returned to defeat the Danes with fresh troops. Cnut's men duly crossed over the Thames Estuary to Essex, the location for the fateful clash that ended in their favor.

Injured in battle, Edmund agreed that Cnut should rule England north of the Thames, and he the south. Within a month, he was dead, perhaps murdered, or maybe from his wounds. 

At Assandun, while Cnut had organized troop formations from the sides, the warrior Edmund was in the thick of battle. After the Dane had been crowned king of England in London in 1017, he paid his respects to his former foe on the anniversary of his death.

Dividing England into four clear regions, each presided over by an earl, Cnut rewarded the prominent Anglo-Saxon families loyal to him while overseeing Wessex himself. Illustration: The Viking Herald

King of England

Now free from Viking raids, England under Cnut enjoyed a period of relative peace and prosperity, allowing the Dane to be granted the later epithet, 'the Great.' 

Edmund's sons fled the country, and Cnut consolidated his status by marrying Aethelred's widow, Emma, daughter of Richard the Fearless of Normandy. 

As the wife of the former monarch and then his successor, this Norman noblewoman would be the queen of England between 1002 and Cnut's death in 1035, with short breaks while Sweyn and Edmund ruled. 

She also assumed control after Cnut while their teenage son, Harthacnut, was still in Denmark, thus setting her against Cnut's second-born by Aelfgifu, Harold Harefoot.

At the start of his English reign, Cnut raised substantial sums in Danegeld to pay his victorious army and send much of the force back to Scandinavia. 

Dividing England into four clear regions, each presided over by an earl, Cnut rewarded the prominent Anglo-Saxon families loyal to him while overseeing Wessex himself. 

A sense of stability was underscored by his good relations with the Church. Later, in 1027, he would visit Rome, for the accession of Conrad II.

Back to Scandinavia

With England in a more stable situation, Cnut could turn his attention to Scandinavia. While both Sweyn and Cnut had been conquering England, son and sibling Harald Svendsen had overseen matters in Denmark, assuming the throne as Harald II in 1014.  

His death in 1018, perhaps at the hands of his brother, allowed Cnut to claim the Danish crown, too, to create a convenient union with England. Leaving his brother-in-law, the Dane Ulf Jarl, as Regent, but selecting his son Harthacnut as heir, Cnut left for England.

In his absence, Norwegian king Olaf Haraldsson, who had wrested control of his country back from the Danes in 1016, saw an opportunity. 

Launching continuing raids against Denmark, the later Saint Olaf eventually faced a huge naval force gathered by Cnut at the Battle of the Helgeå in 1026. Led by Ulf Jarl, the combined English and Danish fleet triumphed over their Norwegian and Swedish opponents, making Cnut the dominant player in Scandinavia.

Behind the scenes, Ulf Jarl had been taking advantage of his stewardship of the young Harthacnut to rule Denmark. Shortly after their joint triumph at sea, Cnut had his compatriot killed on Christmas Day, 1026.

When writing a proclamation to his English subjects as he returned from Rome in 1027, Cnut referred to himself as the king of England, Denmark, the Norwegians, and some Swedes. 

Although Olaf Haraldsson had survived the naval battle of 1026, he then succumbed to Cnut once more when the English monarch sent his fleet to Norway's then capital of Trondheim to successfully claim the Norwegian throne in 1028.

King of sea and lands

Cnut's audience with Conrad II in Rome in 1027 had been another political masterstroke, having his daughter Gunhilda marry his son and heir, Henry III, and pleasing the English Church by having tolls reduced for pilgrims passing through Gaul on their way to Rome.

As monarch of three nations, Cnut gave rise to his most famous legend, commanding the waves to stop before him as he sat by the shore. If this happened, possibly in 1028, perhaps at Thorney Island or Bosham, it may have been a ruse to show his courtiers that he was not omnipotent despite his status as king of kings, and thus demonstrated the supreme power of God.

Cnut died in Dorset in 1035, probably aged around 45, having ruled England and Denmark for the best part of two decades. He was buried in Winchester, where the Normans began to build a magnificent cathedral on the site of the original church from 1079 onwards. Cnut's remains were kept in the mortuary.

Six centuries later, Roundhead soldiers in the English Civil War broke open the chests and scattered the bones of various royals across the floor. 

They were later collected and replaced, with some margin for error. 

Today, hundreds of thousands visit the permanent Kings and Scribes exhibition every year at Winchester Cathedral, England's first Royal Mausoleum. 

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